Flowserve PA46 - Manual (Page 7)

7
Explanatory Notes
 continued 
Description
Intermittent valves for manual or automatic and programmecontrolled removing of boiler sludge from
land or marine installations, particularly if these installations are operated without constant supervision
in accordance with TRD 604. Sludge sediments, which are accumulated precipitates from boiler water
that settle at the bottom of the boiler, will be removed from the steam boiler with the the aid of valves
PA and MPA. These valves give the boiler a short blow at regular intervals, thereby discharging
accumulated sludge and sediments.
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PA 46 and PA 47 are designed for manual operation (diaphragm actuator can be retrofitted).
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MPA 46 and MPA 47 feature a diaphragm actuator for compressed air or pressurized water.
The intermittent valves for removing boiler sludge PA 46 and PA 47 are openend by means of a hand
lever. A pressure pin forces the springloaded valve plug out of the valve seat. The large cross
sectional area of the orifice creates a suction effect, giving a shortterm high water flow which will
discharge the precipitated sludge and sediments and  if installed  move them to a mixing cooler
(= blowdown receiver). The intermittent valve for removing boiler sludge must be completely opened
for about  seconds with the aid of the hand lever in order to give the boiler a short and highly
effective blow.
The intermittent valves for removing boiler sludge MPA 46 and MPA 47 are openend by the diaphragm
actuator. The guide pin of the diaphragm actuator acts upon the pressure pin, which in turn forces the
springloaded valve plug out of the valve seat. The large crosssectional area of the orifice creates a
suction effect, giving a shortterm high water flow which will discharge the precipitated sludge and
sediments and  if installed  move them to a mixing cooler (= blowdown receiver). Compressed air
(at room temperature) or pressurized water (at room temperature) can be used as control fluid for the
diaphragm actuator in accordance with the specified pressure and temperature ratings (see diagram
on page ).
The duration of the bottom blowdown, i. e. the time when the valve is open, should be approx.
 seconds. The time period when the valve remains closed and hence the frequency of the bottom
blowdown must be established as a function of the size and capacity of the steam boiler. We
recommend that approx. 0 per cent of the total amount of boiler water to be removed is discharged
via the intermittent valve for removing boiler sludge.
The duration and frequency of the bottom blowdown must be established individually by the user
as a function of the size and capacity of the steam boiler, the boiler water quality and the
corresponding load.
Function